(i) Technical Field
The present invention relates to an image reading apparatus, an image forming apparatus, and an image reading method.
(ii) Related Art
Hitherto, in image reading apparatuses for reading an image of a document, shading correction is performed on image data that is read by an image reading unit in a first-order manner in order to eliminate the effect of uneven characteristics of an optical system and imaging system of the image reading unit. Correction data serving as a base of the shading correction is generated on the basis of white reference data, which is obtained by capturing, with the image reading unit, an image of a white reference plate provided at a document read position.
However, the white reference plate is provided in a transport path in which documents are constantly transported, and thus dust adhered onto the documents inevitably causes degradation, such as stains and blemishes, on the surface of the white reference plate. In order to obtain white reference data used for performing accurate shading correction, it is necessary to eliminate the effect of such degradation of the white reference plate.